02/19/2013

The new coronavirus: SARS-like? SARS-related? SARS-ish?

A word on semantics this morning, as we wake up to the news of a sixth death from the novel coronavirus.

In recent days, Gregory Hartl, a spokesperson with the World Health Organization, has been busily tweeting at people who have been describing the novel coronavirus as a "SARS-like" virus:

Quick backgrounder: a potentially-deadly new virus that first emerged in the Middle East has infected 12 people since April 2012. Six people have now died -- although the latest victim reportedly had an underlying medical condition that may have made him more susceptible to disease.

Dubbed HCoV-EMC, this new virus is a coronavirus; the virus that caused the SARS outbreak is also a coronavirus. Hence, "SARS-like."

But, as Hartl points out, this new coronavirus differs in many ways from the SARS coronavirus. He explained why in an email:

1. Transmissibility: so far we have only seen sporadic human cases; this coronavirus does not seem to have acquired the ability to transmit easily between humans; indeed, since the beginning of this event we have only had 12 human cases (first ones ten months ago).

2. This virus also seems to cause in some cases renal failure, which SARS did not.

3. We do not know for sure that the reservoir of this coronavirus is bats – in fact we do not know at all what the reservoir is and this is one of the conclusions of the EMRO/Cairo meeting – so this is not the same as SARS.

4. SARS and HCoV-EMC are genetically different.

Here's another way of thinking about it; the common cold is also caused by coronaviruses, the same viral family as SARS. So technically, they could also be described as "SARS-like" -- but common cold viruses cause, well, the common cold. SARS can be fatal and the 2002-2003 outbreak killed approximately 800 people.

But there are similarities to be considered as well: both viruses cause severe respiratory illness. There is strongevidence
to suggest that both viruses originated in bats. And the beginning of the
SARS outbreak was a sputtering one, with just a handful of cases --
something we may also now be seeing with the new coronavirus.

And according to Dr. Matthew Frieman, a microbiologist wtih the University of Maryland, there are only two known human coronaviruses that can cause severe illness in healthy people: SARS and the new coronavirus (although some coronaviruses that cause mild disease in healthy folks can be fatal in the immunocompromised).

Here's what Frieman has to say on whether SARS and EMC are similar or different viruses (his response has been edited and condensed):

The similar and different thing is funny because it depends what you're talking about. It's closer to SARS than it is to, say, Ebola virus, right? But it's not SARS.

But, it's closer to SARS than it is to a lot of other coronaviruses -- there are three groups to coronaviruses and it's in the same group as SARS. It's just the way you want to pitch it -- if you want to scare people and say it's SARS-like, you say it's SARS-like.

SARS taught the world some valuable lessons: that coronaviruses can be deadly; that there are new coronaviruses yet to be discovered; and, most importantly, that the world cannot afford to be complacent when a new coronavirus emerges.

So, on the one hand, it is important to remember SARS going forward -- nobody wants to see another outbreak or a repeat of the mistakes that were made.

But calling the new virus "SARS-like" is potentially fear mongering and, as far as we know, the new virus has only infected a dozen people and killed six. To put things in perspective, the WHO estimates that the seasonal flu kills between 250,000 and 500,000 people a year. Since 2003, the avian flu has also killed 367 people out of 620 confirmed cases.

I agree that "SARS-like" is flawed as a descriptor and somewhat misleading. But I do think SARS is relevant to mention as we continue discussing this new coronavirus.

So, perhaps: "SARS-related"?

Jennifer Yang is the Toronto Star’s global health reporter.
She previously worked as a general assignment reporter and won a NNA in
2011 for her explanatory piece on the Chilean mining disaster. Follow
her on Twitter: @jyangstar

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